Synergistic Promotion of Large-Current Water Splitting through Interfacial Engineering of Hierarchically Structured CoP−FeP Nanosheets with Rich P Vacancies

Graphical A CoP−FeP heterostructure catalyst with abundant P vacancies (Vp−CoP−FeP/NF) on nickel foam is constructed through impregnation and phosphorization. It demonstrates excellent hydrogen evolution performance and has practical application prospects in high-current overall water splitting. The catalyst‘s unique hierarchical nanosheet structure, plentiful P vacancies and synergistic effect of CoP and FeP accelerate HER kinetics, resulting in its superior performance. The development of hydrogen evolution reaction (HER) catalysts with high performance under large current density is still a challenge. Introducing P vacancies in heterostructure is an appealing strategy to enhance HER kinetics. This study investigates a CoP−FeP heterostructure catalyst with abundant P vacancies (Vp−CoP−FeP/NF) on nickel foam (NF), which was prepared using dipping and phosphating treatment. The optimized Vp−CoP−FeP catalyst exerted prominent HER catalytic capability, requiring an ultra-low overpotential (58 mV @ 10 mA cm −2 ) and displaying robust durability (50 h @ 200 mA cm −2 ) in 1.0 M KOH solution. Furthermore, the catalyst demonstrated superior overall water splitting activity as cathode, demanding only cell voltage of 1.76 V at 200 mA cm −2 , outperforming Pt/C/NF (−) || RuO 2 /NF (+) . The catalyst‘s outstanding performance can be attributed to the hierarchical structure of porous nanosheets, abundant P vacancies, and synergistic effect between CoP and FeP components, which promote water dissociation and H* adsorption and desorption, thereby synergically accelerating HER kinetics and enhancing HER activity. This study demonstrates the potential of HER catalysts with phosphorus-rich vacancies that can work under industrial-scale current density, highlighting the importance of developing durable and efficient catalysts for hydrogen production.